1. Field of the Invention
This invention relates to obstetric device and methods and more particularly to a safe, sterile device that may be employed to obtain samples of exfoliated fetal tissue from the uterine cavity.
2. Description of the Prior Act
The obstetric arts have long sought a safe, simple, method applicable on a mass basis to obtain sample tissue during pregnancy in order to permit prenatal diagnosis of genetic diseases. Amniocentesis is the method now employed to perform such prenatal diagnoses. This method, which involves securing a sample of the amniotic fluid, has several disadvantages. In addition to the undesirable aspect of requiring that the abdominal wall, uterus, and amniotic membrane be permeated with a needle in order to obtain the sample, the procedure cannot be employed until the fetus has reached a certain size, thereby ruling out first trimester screening.
Thus, the current state of the art does not provide a device or method that can be used for first trimester screening of pregnant females in order to identify fetuses developing with a chromosomal disorder.
A variety of devices have been suggested for gynecological use to sample vaginal, cervical or uterine tissue for the presence of cancer cells. Such devices are designed to obtain tissue samples which are then fixed (killed and preserved) onto glass slides for examination by a pathologist under a microscope. In contrast with such a gynecological cell sampling procedure, antenatal cells gathered for genetic examination are not fixed but rather are cultured in an incubator before examination for genetic disorder.
Thus, the prior art gynecological tools have been designed without regard for contamination by bacteria (since bacteria would be killed during the cell fixing practice in any case). In contrast, with antenatal cells, the presence of even a single bacterium cell in the fetal tissue culture could destroy the entire specimen, and thus maintenance of sterility is the quintessence of a satisfactory antenatal cell extracting method and device.
As noted, the prior art gynecological cell sampling devices have as their objective the obtaining of sample cells from the female, rather than the accumulation of fetal cells. Since the gynecological tools as described were designed to be used in a non-pregnant reproductive tract, they have been designed without regard for the importance of avoiding any effect on the pregnant state of the carrier female. Thus, such gynecological tools have utilized rigid or scratchy projections to scrape or aspirate tissues onto or into the sampling device (See, e.g., U.S. Pat. Nos. 3,838,681; 3,664,328; 3,800,781; and 3,877,464.)
U.S. Pat. No. 3,857,384 inserts a microscope slide so that the cervical specimen is obtained directly as a smear on the slide for cytologic evaluation. U.S. Pat. No. 3,777,743 employs negative suction to draw sample cells into the device for subsequent examination. Such an approach of utilizing negative suction to draw sample cells into the device would be totally unsuited for use in a antenatal cell gathering device because of the danger, particularly during the early stages of pregnancy, that the pregnancy would be adversely affected and indeed, possibly terminated by the use of the procedure.
Accordingly, it is a primary object of this invention to obtain a device for gathering fetal cells during the early stages of pregnancy.
Another object is to provide a device of the character described which may be safely employed without risk of adversely affecting the pregnancy.
A further object is to provide a device of the character described which is sterile and can be used without risk of contamination.
A still further object of the invention is to provide an antenatal cell extracting device which may be employed as a mass screening test for virtually all pregnant mothers during the first trimester of pregnancy in order to diagnose the presence of fetal sex and genetic disease at an early stage.